Conventionally, in the production of semiconductor devices, microfabrication by lithography using a photoresist has been carried out. The microfabrication is a machining process in which a thin film of a photoresist is formed on a semiconductor substrate such as a silicon wafer, active light such as ultraviolet light is applied onto the substrate through a mask pattern with a pattern of a semiconductor device followed by development, the substrate is etched using the obtained photoresist pattern as a protective film, and a fine concave-convex corresponding to the pattern is consequently formed on the substrate surface.
In recent years, semiconductor devices have been further integrated, and the active light to be used has changed from an excimer laser (248 nm) to an ArF excimer laser (193 nm) that has a shorter wavelength. Such a change has raised a problem of the effect of reflections of active light from a semiconductor substrate. To address the problem, a method for providing an anti-reflective coating (bottom anti-reflective coating) between a photoresist and a substrate has been widely studied.
As the photoresist underlayer film between a semiconductor substrate and a photoresist, a film that contains a metallic element such as silicon and titanium and that is known as a hard mask has been used (for example, see Patent Document 1). In this case, components are greatly different between the resist and the hard mask and, when the resist and the hard mask are removed by dry etching, each removal rate largely depends on gas species used in the dry etching. On this account, appropriate selection of gas species enables the hard mask alone to be removed by dry etching without large reduction in the film thickness of the photoresist.
In this manner, in recent production of semiconductor devices, a resist underlayer film has been provided between a semiconductor substrate and a photoresist in order to achieve various effects including anti-reflection effect. Thus, a composition for the resist underlayer film has been studied. However, there is a demand for a new material for the resist underlayer film due to a wide variety of characteristics required.
For example, a composition and pattern formation method using a compound having a silicon-silicon bond are known (for example, see Patent Document 2).
An anti-reflective coating material that includes a light absorbable silicone resin having a weight average molecular weight of 30,000 or less and containing a constituent having a molecular weight of less than 600 in an amount of 5% or less based on the total amount, a first acid generator having a decomposition temperature of 200° C. or less, and an organic solvent is disclosed (for example, see Patent Document 3).